This invention relates to formulations and particularly, although not exclusively, relates to liquid formulations, methods of producing mixed liquid formulations and apparatus therefor.
WO2008/078079 describes a method of selecting a non-volatile liquid colour formulation for manufacturing a plastic part. The publication also discloses a method of manufacturing the colour formulation using a colour dispense system which includes more than ten base colour formulations which are dispensed in predetermined amounts into a receptacle, in order to define, when mixed, a desired colour.
Various different types of receptacles are in commercial use for delivering liquid formulations. For example, WO2008/078075 describes use of a circular cross-section pail having a wide diameter opening closed by a lid. Components of formulations may readily be introduced into the pail and mixed using a bladed stirrer because the opening to the pail is so wide. However, pails tend to use a substantial amount of material in their manufacture due to the need for them to be self-supporting and, consequently, tend to be heavy and they are not always readily recycled. Furthermore, in view of their circular cross-section, an array of pails takes up significantly more volume than the volume of their contents and, accordingly, transport costs may be increased compared to a situation wherein suitable receptacles could be packed together more efficiently.
Receptacles which comprise a so-called “bag-in-a-box” are well known. These comprise a collapsible plastics inner receptacle having a narrow diameter inlet/outlet opening for passage of liquid into and out of the inner receptacle and an outer cuboid cardboard box in which the inner receptacle is arranged with its inlet/outlet opening projecting through the box to the outside. Advantageously, bag-in-a-box receptacles can be packed together very efficiently and are readily recycled after use. However, there are disadvantages associated with such receptacles. Firstly, due to the narrow diameter of the inlet/outlet opening, it is not possible using the colour dispense system of WO2008/078079 to dispense base colour formulations from their individual dispense heads directly into a receptacle. So, if it is desired to use a bag-in-a-box receptacle, the colour dispense system must dispense the base colour formulations into an intermediate receptacle (e.g. it may be a pail). After mixing of the base colour formulations in the intermediate receptacle, mixed formulation may be decanted or piped into the bag-in-a-box receptacle which can then be shipped to a customer for use.
A second disadvantage associated with the bag-in-a-box receptacles has, after tests, been appreciated by the Applicant, namely that complete mixing of the contents of such receptacles can be difficult if the integrity of the receptacle is to be maintained. For example, it has been found that shaking, rotating or application of a vibratory force to such a receptacle causes the bag part of the receptacle to move within the box part of the receptacle which, over a short period of time, damages the box part by penetrating the cardboard or compressing it and making it floppy or not self-supporting. As a result, the box part would need replacing before shipping to a customer which is impractical. In addition, corners of the bag part of such a receptacle tend to comprise thinner material, as a result of the blow moulding process used in their manufacture. The corners tend to be subjected to more impact as the bag part moves within the box part which risks penetration of the bag part and/or leakage. Thus, it is difficult to use a bag-in-a-box receptacle when the content of the receptacle needs to be vigorously mixed after introduction into the receptacle.
It is an object of the present invention to address the above described problems.